Vehicle cab noise suppressing system

ABSTRACT

A vehicle cab noise suppressing system includes a cab interior panel having an opening exposed to acoustic noise in the cab, an acoustic resonator chamber, and a conduit communicating the resonator chamber to the opening. The resonator chamber is formed by a plurality of walls which are spaced apart from the interior panel and which are formed by a second panel. A third panel cooperates with the walls to enclose the resonator chamber. The chamber volume and the diameter and length of the conduit are chosen so as to acoustically tune the chamber to a noise frequency in the cab and thereby reduce noise in the cab.

BACKGROUND

The present invention relates to a vehicle cab noise suppression system.

Many off-road vehicles have cabs which enclose a certain volume, and theenclosed volume will have an acoustic resonance which causes a “booming”noise. Such a noise is annoying to vehicle operators and can reduceoperator productivity.

Resonators have been used with exhaust mufflers and combustion airintake systems which have a given sound frequency traveling through themuffler or intake tubes. When the noise reaches the resonator, theresonator reflects the noise back, preventing it from continuing downthe system. This reduces exhaust noise and intake noise, and is used inmufflers and air intakes. In the construction field, large warehouses orbuildings will have a slot in the cinder blocks of a wall and a volumebehind the slot. This slot and volume acts as a resonator external tothe volume where the noise is generated. This reduces the noise in thebuilding. Heretofore, such techniques have not been applied to reducenoise in a vehicle cab.

SUMMARY

Accordingly, an object of this invention is to reduce or eliminate thebooming noise in the cabs of off-road vehicles.

A further object of the invention is to provide a noise suppressingpanel assembly provide which reduces acoustic resonance in the cab ofoff-road vehicles.

A further object of the invention is to provide a vehicle cab roof panelassembly which reduces acoustic resonance.

These and other objects are achieved by the present invention, wherein avehicle cab noise suppressing system includes a cab interior panelhaving an opening exposed to acoustic noise in the cab, an acousticresonator chamber, and a conduit communicating the resonator chamber tothe opening. The resonator chamber is formed by a plurality of wallswhich are spaced apart from the interior panel and which are formed by asecond panel. A cover panel cooperates with the walls to enclose theresonator chamber. The chamber has a volume and the conduit has adiameter and length which are chosen so as to acoustically tune thechamber to a noise frequency in the cab and thereby reduce noise in thecab. The interior panel is preferably a cab roof headliner. A trim coveris mounted in a depression in the interior panel which surrounds theopening.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the underside of cab roof assemblyincluding a noise suppression system according to the present invention;

FIG. 2 is a perspective view of the underside of the cab roof assemblyof FIG. 1 with the head liner removed;

FIG. 3 is a partial cut-away top view of the cab roof assembly of FIG.1;

FIG. 4 is a view similar to FIG. 3, but with portions of the coverpanels removed;

FIG. 5 is a perspective view along lines 5-5 of FIG. 3;

FIG. 6 is a view in the direction of lines 6-6 of FIG. 5 with the trimcover removed for clarity; and

FIG. 7 is a back side perspective view of the trim cover of FIG. 5.

DETAILED DESCRIPTION

Referring to FIG. 1, the cab roof assembly 10 includes a top roofhousing 12 which covers an inner roof member 14. A head liner 16 isattached at its outer periphery to a lower surface of inner roof member14. The head liner 16 includes a front portion 5, a rear portion 7, aleft portion 9 and a right portion 11. Inner roof member 14 forms a pairof chambers 18 and 20 which in FIG. 1 are hidden behind the head liner16. A pair of trim covers 22 and 24 are mounted in depressions formed inthe head liner 16. The cab roof assembly 10, inner roof member 14 andhead liner 16 all have generally rectangular shapes forming diagonallyseparated corners.

The headliner 16 includes an outer rim portion 13 defining a firstsurface, a central inner portion 15 defining a second surface which isspaced apart from the first surface, and a transition wall 17 whichsurrounds an outer edge of the inner portion 15 and joins the innerportion 15 to the outer portion 13. The transition wall 17 surrounds agenerally rectangular-shaped recess with four side walls joined at fourcorners 19, 21, 23 and 25. The longest internal dimensions of the roofassembly 10 extend generally diagonally through opposite pairs of thesecorners. Openings 31 and 33 are formed in the transition wall 17adjacent to corners 25 and 23, respectively, but in FIG. 1 theseopenings are hidden behind trim covers 22 and 24.

As best seen in FIG. 2, inner roof member 14 forms a plurality of walls30-40 which partially surround chamber 18. The inner roof member 14 alsoforms a plurality of walls 42-50 which partially surround chamber 20.The inner roof member 14 also forms a hollow conduit 52 which extendsfrom chamber 18 to trim cover 20, and a hollow conduit 54 which extendsfrom chamber 20 to trim cover 24. Trim covers 20 and 24 each have aplurality of apertures 84 which communicate with the interior of theconduits 52 and 54.

Referring now to FIGS. 3 and 4, the chambers 18 and 20 are covered byrespective cover panels 60 and 62 which are attached to the uppersurface of inner roof member 14.

As best seen in FIG. 5, the conduit 52 includes an inner portion 64which projects into chamber 18 and an outer portion 66 which projectsout of chamber 18. The head liner 16 includes a depression 63 whichsurrounds opening 31 which receives an outer end of the conduit 52 andwhich receives a portion of the trim cover 22.

As best seen in FIG. 6, inner roof member 14 forms three axiallyextending mounting bosses 68, 70 and 72 which are spaced around theperiphery of a bore 74 which extends through conduit 52. Inner roofmember 14 also forms three slots 76, 78 and 80 in the conduit 52, eachof which is positioned adjacent a corresponding one of bosses 68, 70 and72. The head liner 16 is lined with pads 67 and 69 of sound absorbingmaterial.

As best seen in FIGS. 5 and 7, trim cover 22 includes a circular head 82with a plurality of apertures 84 formed therein, and hollow mountingposts 86, 88 and 90 which project from the rear side of head 82. Thetrim cover 22 is attached to the bosses 68-72 by screws (not shown)which extend through the mounting posts 86-90 and into the bosses 68-72.The head liner 16, the apertures 84, openings 31 and 33 are exposed toacoustic noise in the interior 55 of the cab (not shown). Preferably,the apertures 84 are large enough so that they do not completelyrestrict the air from moving into and out of the chambers 18 and 20.

The chambers 18 and 20 operate as acoustic resonators which areacoustically connected to an interior of the head liner 16 via theconduits 52 and 54, the openings 31 and 33 in the head liner 16 and theapertures 84 in the respective trim covers 22 and 24. Each chamber actslike a Helmholtz resonator which interacts with acoustic noise modes ofa vehicle cab. The volume of chambers 18 and 20 and the diameter andlength of the conduits 52 and 54 are chosen so as to “tune” theresonator to a noise frequency in the cab. The chambers are preferablylocated behind the head liner 16 to the left and right of the operator'shead. Preferably, so as to best suppress noise under the cab roofassembly 10, the trim covers 22 and 24 and the associated openings 31and 33 are located near the corners 19-25 and adjacent to lines whichconnect opposite corners of the roof assembly 10. A pair of suchresonators have shown a reduction in cab “booming” noise of 3 to 5decibels at a 100Hz frequency.

While the present invention has been described in conjunction with aspecific embodiment, it is understood that many alternatives,modifications and variations will be apparent to those skilled in theart in light of the foregoing description. Accordingly, this inventionis intended to embrace all such alternatives, modifications andvariations which fall within the spirit and scope of the appendedclaims.

Assignment

The entire right, title and interest in and to this application and allsubject matter disclosed and/or claimed therein, including any and alldivisions, continuations, reissues, etc., thereof are, effective as ofthe date of execution of this application, assigned, transferred, soldand set over by the applicant(s) named herein to Deere & Company, aDelaware corporation having offices at Moline, Ill. 61265, U.S.A.,together with all rights to file, and to claim priorities in connectionwith, corresponding patent applications in any and all foreign countriesin the name of Deere & Company or otherwise.

1. A vehicle cab noise suppressing system, comprising: a cab interiorpanel having an opening exposed to acoustic noise in the cab; anacoustic resonator chamber; and a conduit communicating the resonatorchamber to the opening.
 2. The noise suppressing system of claim 1,wherein: the resonator chamber is formed by a plurality of walls whichare spaced apart from the interior panel.
 3. The noise suppressingsystem of claim 1, comprising: a second panel having a plurality ofwalls which are spaced apart from the interior panel; a third panelcooperating with the walls to enclose the resonator chamber.
 4. Thenoise suppressing system of claim 1, wherein: the chamber has a volumeand the conduit has a diameter and length which are chosen so as toacoustically tune the chamber to a noise frequency in the cab andthereby reduce noise in the cab.
 5. The noise suppressing system ofclaim 1, wherein: the interior panel comprises a cab roof headliner. 6.The noise suppressing system of claim 1, wherein: the interior panelcomprises a cab roof headliner having an outer rim portion defining afirst plane, a central inner portion defining a second plane which isspaced apart from the first plane, and a transition wall which surroundsan outer edge of the inner portion and joins the inner portion to theouter portion, and the opening is formed in the transition wall.
 7. Thenoise suppressing system of claim 1, further comprising: a trim covermounted in the opening of the interior panel.
 8. The noise suppressingsystem of claim 7, wherein: the trim cover includes an aperture whichcommunicates sound through it to the conduit.
 9. The noise suppressingsystem of claim 1, wherein: the interior panel comprises a depressionsurrounding the opening; and a trim cover is mounted in the depression.10. The noise suppressing system of claim 1, wherein: the interior panelforms a recess having a generally rectangular shape with diagonallyseparated corners; and the opening and the conduit are located adjacentto one of the corners.
 11. A vehicle cab noise suppressing system,comprising: a cab interior panel having a generally rectangular shapeforming diagonally separated corners, the cab interior panel having apair of openings exposed to acoustic noise in the cab, and the openingsbeing located adjacent lines connecting opposite pairs of said corners;a pair of acoustic resonator chambers; and a pair of conduits, eachcommunicating one of the resonator chambers to a corresponding one ofthe openings.
 12. The noise suppressing system of claim 11, wherein:each resonator chamber is formed by a plurality of walls which arespaced apart from the interior panel.
 13. The noise suppressing systemof claim 11, comprising: a second panel having a plurality of wallswhich are spaced apart from the interior panel; a third panelcooperating with the walls to enclose the resonator chambers.
 14. Thenoise suppressing system of claim 11, wherein: each chamber has a volumeand each conduit has a diameter and length which are chosen so as toacoustically tune the chamber to a noise frequency in the cab andthereby reduce noise in the cab.
 15. The noise suppressing system ofclaim 11, wherein: the interior panel comprises a cab roof headliner.16. The noise suppressing system of claim 11, wherein: the interiorpanel comprises a cab roof headliner having an outer rim portiondefining a first plane, a central inner portion defining a second planewhich is spaced apart from the first plane, and a transition wall whichsurrounds an outer edge of the inner portion and joins the inner portionto the outer portion, and the openings are formed in the transitionwall.
 17. The noise suppressing system of claim 11, further comprising:a pair of trim covers, each mounted in a corresponding one of theopenings.
 18. The noise suppressing system of claim 17, wherein: eachtrim cover includes an aperture which communicates sound through it tothe corresponding conduit.
 19. The noise suppressing system of claim 11,wherein: the interior panel comprises a pair of depressions, eachsurrounding a corresponding one of the openings; and each trim cover ismounted in one of the depressions.
 20. The noise suppressing system ofclaim 11, wherein: the acoustic resonator chambers extend towards eachother from each respective conduit.
 21. The noise suppressing system ofclaim 11, wherein: the openings are located adjacent an adjacent pair ofsaid corners.
 22. A vehicle cab noise suppressing system, comprising: acab interior panel forming a recess, the recess having a generallyrectangular shape forming diagonally separated corners, the cab interiorpanel having a pair of openings exposed to acoustic noise in the cab,and the openings being located near an adjacent pair of said corners; apair of acoustic resonator chambers; and a pair of conduits, eachcommunicating one of the resonator chambers to a corresponding one ofthe openings.